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Biofuels may hold the key to reducing our dependence on foreign oil and cutting down on our greenhouse gas emissions. Ethanol is currently the biofuel of choice, with almost all gasoline bought at the pump in the United States containing 10 percent ethanol. Right now, though, most ethanol comes from corn and sugarcane, and there are concerns that growing our fuel from these crops could drive up food prices (“food versus fuel”).

Biofuels made from macroalgae, aka seaweed, avoid this problem. Seaweeds do not require arable land, fertilizer, or fresh water, and they are already cultivated as food (though not a staple crop like corn), animal feed, fertilizers, and sources of polymers. Traditionally, scientists ignored seaweed as a biofuel source because its main sugar component was too difficult to process. A recent paper published by Science describes how researchers genetically-engineered a microbe that is capable of producing ethanol from seaweed.

The so-called second generation of bioethanol is derived from inedible crops like wood and switchgrass, or the inedible portions of food crops like corn (the leaves and stalks). However, this cellulosic material is difficult to process due to the presence of lignin in the cell walls—although we reported on some attempts to genetically modify switchgrass to make this easier. Seaweed doesn’t contain lignin, making processing a lot easier and enabling higher yields: a Department of Energy study showed that, under ideal conditions, seaweed could produce twice the ethanol that we get from sugarcane and five times the amount from corn.

You may be asking “This sounds great, why aren’t we making ethanol from seaweed?” Well, there is a catch. Seaweeds contain three primary sugars: alginate, mannitol, and glucose. Right now, existing industrial microbes can’t metabolize alginate, so ethanol yields are severely limited.

At this point, most people would stop and say “Well, maybe seaweeds aren’t the best way to produce biofuels.”

On the other hand, if you were Adam Wargacki and a team of 13 others from the Bio Architecture Lab, you wouldn't stop. Instead, you’d look to the well-known bacterium Escherichia coli (E. coli), which has a natural ability to metabolize mannitol and glucose. Since we know of enzymes that can process alginate (alginate lyase and oligoalginate lyase), Wargacki et al apparently thought “We can make this work.”

There are several bacteria species with known alginate metabolic systems, but only one where we've identified an alginate transport system to get it inside of cells: Sphingomonas sp. A1. Unfortunately, this system is too large and complex to be incorporated into E. coli.

Now, a 30-kbp DNA fragment is too long to directly clone into E. coli, and the function of the genes in that DNA hasn’t been described yet. To get E. coli with the right DNA, the authors created a library of random DNA fragments from the V. splendidus genome. Each fragment is carried by DNA called a fosmid, which will stably integrate a 40-kbp piece of DNA into a target’s genome. After inserting the fosmid library into E. coli, they placed the bacterial colonies into a medium where alginate was the only food source. Only colonies with a particular fosmid (designated pALG1) grew, suggesting that this section of DNA contained the 30-kbp piece they identified earlier.

After this, they checked the individual protein coding sections of pALG1 to determine the function of each. By deleting them one at a time and testing for the ability to grow on alginate, they were able to identify an alginate transport system that hadn’t previously been described.

After inserting these genes into a strain of E. coli, they took genetic pathways for ethanol production from Zymomonas mobilis—through enzymes called pyruvate decarboxylase and alcohol dehydrogenase B, for those interested—but deleted some pathways that produced undesired byproducts. Finally, they tested their engineered E. coli strain (which they named BAL1611), in a five percent sugar mixture containing alginate, mannitol, and glucose at a ratio of 5:8:1, which represents the typical ratio in brown macroalgae (seaweeds). They found that it produced ethanol at a yield of about 20 grams per liter.

For a final demonstration, they used Saccharina japonica, otherwise known as kombu, a common edible kelp. Their microbe produced ethanol at a ratio of 0.281 grams of ethanol for each gram of algae—which is over 80 percent of the theoretical yield. In addition, 83 percent of the yield was obtained within 48 hours.

This study may have opened the door to using seaweed as a source of ethanol—there is certainly a lot of potential here. Even more fascinating is the approach to engineering a microbe to give it the characteristics we desire.

Hopefully, microbes can eventually be engineered to make more than just ethanol. It is much less energy dense than gasoline, so current vehicles can’t burn a fuel mix that contains more than about 15 percent ethanol. Butanol, on the other hand, is much more similar to gasoline, so perhaps a future microbe may produce that.

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Kyle Niemeyer
Kyle is a science writer for Ars Technica. He is a postdoctoral scholar at Oregon State University and has a Ph.D. in mechanical engineering from Case Western Reserve University. Kyle's research focuses on combustion modeling. Emailkyleniemeyer.ars@gmail.com//Twitter@kyle_niemeyer

Cool. So when these get released into the wild they'll dissolve every last piece of algae in our oceans and elevate the alcohol content to levels toxic to all denizens thereof. But the good news is we'll be able to drink seawater and get shitfaced.

I wonder if producing methane would not be more useful - we already have an extensive infrastructure, and the resulting fuel could be used not just in current vehicles (with minor modification) but also in any heating, cooking, and power generation applications.

Can E. Coli survive the salinity of ocean water? Do the researchers put the e. coli strain into the saltwater tanks with the seaweed, or do they take the seaweed out, rinse it off, and put the desalinated seaweed and e. coli into another tank?

I could be wrong, but I thought salt water and sunlight tend to kill off e. coli, so Putrid Polecat's concern might not be an actual potential problem?

And yet, the oceans don't seem to be dieing from naturally occuring e. coli (that is, the bacteria might be present, but something keeps it in some sort of equilibrium level?). There must be some sort of natural limit on e. coli in the oceans?

I don't think we should jump to the conclusion that this will necessarily be a massive ecological disaster. . . nor should we probably jump to the conclusion it's safe. I'd say we just need to be sure that it would be kept naturally in check, first. I.e. "needs more study". *grin*

I wonder if producing methane would not be more useful - we already have an extensive infrastructure, and the resulting fuel could be used not just in current vehicles (with minor modification) but also in any heating, cooking, and power generation applications.

No, methane is hard to handle: Not only you have to transport it through either pipelines (expensive) or bulky pressurized cans, it's a potent greenhouse gas when leaked. The energy density is also not as high as ethanol

Isn't butanol what they used to use for race cars back in the 80s? I thought that they switched away from it because it was much more susceptible to igniting (has a wider range of vapor concentrations that can ignite) and that more dangerously, it burns with a clear flame. (I remember seeing footage of a bad fire in the pits where people where jumping around on fire but you couldn't see the flames.)

Biofuel from corn is simply crazy. Sea weed on the other hand is fairly reasonable, and I could see production of biofuel from sea weed being roughly cost comparable to gasoline, especially if that article about Peak Oil was actually true...

Another blind alley. If you're going to burn something in an IC engine, burn natural gas. It requires little expensive processing, is easy to store, and it's easy to modify existing engines to use CNG for a fuel. All IC alt-fuels like this (even CNG) are just steps along the way to all-electric vehicles.

The kelp forests are already under environmental stress. Now we're going to farm the stuff? And process it with an engineered organism that quite readily will munch on the stuff in the wild? When have *any* industrial-grade processes been 100% leak-free?

Cool. So when these get released into the wild they'll dissolve every last piece of algae in our oceans and elevate the alcohol content to levels toxic to all denizens thereof. But the good news is we'll be able to drink seawater and get shitfaced.

A bacteria with all that manipulation isn't going to be competitive in any sort of natural environment. It is designed for a specific niche that only exists in its breeding tanks, send out into the wild and it'll quickly go extinct.

I wonder if producing methane would not be more useful - we already have an extensive infrastructure, and the resulting fuel could be used not just in current vehicles (with minor modification) but also in any heating, cooking, and power generation applications.

No, methane is hard to handle: Not only you have to transport it through either pipelines (expensive) or bulky pressurized cans, it's a potent greenhouse gas when leaked. The energy density is also not as high as ethanol

Well, it's hard-er than liquid fuels, yes. (Though separating it from the production tank would probably be much easier.) But importantly, it's an already-solved problem in that we have a very large infrastructure that already exists dedicated for this task. Even more importantly, it's a far more versatile fuel that's already in use on a large scale in industrial, commerical, and residential settings. Most importantly of all, we have ample fossil reserves that can relatively easily be used to backstop any volatitility in the renewable supply, making it economically promising.

Studies have shown that E. coli not only survives in salt water but thrives in beach sand (very salty). I think this is a very bad idea, spawned from very good intentions.

Faramir wrote:

A bacteria with all that manipulation isn't going to be competitive in any sort of natural environment. It is designed for a specific niche that only exists in its breeding tanks, send out into the wild and it'll quickly go extinct.

The second point.

The real threat is phage. Bacteria have viruses same as macro-organisms do but bacteria don't have the same capacity for individual survival that our own immune response provides. Bacteria survive phage collectively through diversity.

An engineered strain is at a disadvantage compared to wild strains in that regard.

Studies have shown that E. coli not only survives in salt water but thrives in beach sand (very salty). I think this is a very bad idea, spawned from very good intentions.

The E. Coli part bothers me too, but somehow I really doubt the plan would be to use the bacteria while the seaweed is in the ocean... I'm guessing it's grow, harvest, ferment. Like we've done for, oh, a few thousand years with everything else we've fermented .

Politics aside, I'm just fascinated by this article, especially by the details on how the scientists researched the genes that they needed and the details of the process that they went through to get the genes inserted into E. coli. I was under the impression that individual genes (the ones that properly metabolize the sugars available in seaweed) could be inserted at will; I had no idea that you had to insert such large chunks of DNA into a genome at once. It seems like a very difficult project, and one that's almost crazy-making to find a 30kbp DNA segment that does what you want without introducing undesirable effects along with the desired ones.

"Hopefully, microbes can eventually be engineered to make more than just ethanol"

It is more when rather than if. The timing is uncertain. But, it will surely be a Moore's law style phenomenon sometime this century. The end result will be to replace most current chemical technology. Of course, there will be those who shake with fear at this kind of prospect. But the likely outcome is that this kind of technology will be much safer than the chemical technology it replaces.

there are concerns that growing our fuel from these crops could drive up food prices (“food versus fuel”). Biofuels made from macroalgae, aka seaweed, avoid this problem. Seaweeds [...] are already cultivated as food (though not a staple crop like corn), animal feed

Looks like a blatant contradiction. If seaweed is an animal feed, why is it any less of a food than corn? Corn ethanol at current levels doesn't change the amount of animal feed available much. If seaweed has potentional for increased harvesting and can be used to any extent as feed, then that would make it more of a conflict with food supply than corn ethanol is.

And just because seaweed is out of sight, doesn't necessarily mean large quantitiies can be harvested without significant negative impact. It's all these dreams of 'green' (earth friendly) biofuels that allow people to think they don't have to face the reality they are too wasteful.

Quote:

Hopefully, microbes can eventually be engineered to make more than just ethanol. It is much less energy dense than gasoline, so current vehicles can’t burn a fuel mix that contains more than about 15 percent ethanol.

Ah, but ethanol is more efficient than gasoline so future vehicles could get closer to equal useful output. And it is the future we are more concerned with isn't it?

Quote:

This is pretty encouraging!

Biofuel from corn is simply crazy. Sea weed on the other hand is fairly reasonable,

What's really crazy is people talking about things they know nothing about.

Politics aside, I'm just fascinated by this article, especially by the details on how the scientists researched the genes that they needed and the details of the process that they went through to get the genes inserted into E. coli. I was under the impression that individual genes (the ones that properly metabolize the sugars available in seaweed) could be inserted at will; I had no idea that you had to insert such large chunks of DNA into a genome at once. It seems like a very difficult project, and one that's almost crazy-making to find a 30kbp DNA segment that does what you want without introducing undesirable effects along with the desired ones.

They can pretty much insert individual genes at will, the problem is that the gene knowledge at this point does not allow to select individual genes, as the article says, they know 1 block that has what they needed, and they looked for another block which seemed to have those same pieces while being shorter.

Is like having a book where you can understand one paragraph here and another there, and you know the topic of the chapter. You have to select whole chapter full of stuff that you don't understand because it is very likely that if you select only the paragraph that you understand and ignore the rest, then the chapter would be useless.

I had no idea that you had to insert such large chunks of DNA into a genome at once. It seems like a very difficult project, and one that's almost crazy-making to find a 30kbp DNA segment that does what you want without introducing undesirable effects along with the desired ones.

Yes, it's interesting. However, that's not really what they did. They only did that as an intermediate step to identify the part they needed.

Ok. This is really great! But they need to optimize it using evolutionary methods. In a lab they've made e. coli metabolize citrate [using evolutionary methods]... Which it characteristically cannot do. So I am sure they could push the efficiency of this system to 90+ ...

I'm sure the technology is there to convert algae sugars into fuel, but I seriously doubt it will amount to anything on the industrial scale we need to replace part of our current fuel consumption.

For one thing, growing algae requires tremendous amounts of water and the tanks also need a substantial surface area. While pumping water from the ocean could solve the former, there's not many suitable coastal locations that are not arable lands in the U.S.

I'm sure the technology is there to convert algae sugars into fuel, but I seriously doubt it will amount to anything on the industrial scale we need to replace part of our current fuel consumption.

For one thing, growing algae requires tremendous amounts of water and the tanks also need a substantial surface area. While pumping water from the ocean could solve the former, there's not many suitable coastal locations that are not arable lands in the U.S.

Actually, as I mentioned in the article, "Seaweeds do not require arable land, fertilizer, or fresh water..."

I'm sure the technology is there to convert algae sugars into fuel, but I seriously doubt it will amount to anything on the industrial scale we need to replace part of our current fuel consumption.

For one thing, growing algae requires tremendous amounts of water and the tanks also need a substantial surface area. While pumping water from the ocean could solve the former, there's not many suitable coastal locations that are not arable lands in the U.S.

But, "arable" land means it has sufficient soil and fresh water. If your "crop" grown in tanks full of seawater, you don't need arable land, by definition.

Biofuel from corn is simply crazy. Sea weed on the other hand is fairly reasonable, and I could see production of biofuel from sea weed being roughly cost comparable to gasoline, especially if that article about Peak Oil was actually true...

Here's the issue with seaweed:1) landmass. It might be limited, but if you want to grow on water, what do you think it would take to set up a couple thousand square mile sized farm on open water, huh? Where most of it wouold be in international waters due to it;s size? Think of a water based farm the size of, i don't know, 5 STATES in land mass... That's what it would take, roughly, to replace land-based ethanol2) Crops grow up, not just out. And fast. Seaweed is relatively slow growing compared to switchgrass, lower yield per gram, and grows mostly flat on the surface, so the physical yield of material per acre is less volume, each acre produces fewer rotations per year, and cost to harvest is massive, and yields are a fraction of regular crops.3) a seaweed crop that massive will have uncoutable environmental effects. It would alter water temps, screw with feeding grounds, totally fuck with the fishing industry, and have massive environmental impact putting tens of thousands of craft on the water each becoiming en ecologic disaster potential. A tractor leaks oil and its not a huge deal, a boart does and things change...

What does work: MAKING fuel, chemically. We've been doing it for decades. Its about $4-5 a gallon useing the latest tech, requires little land mass, is environmentally sound (about a quarter the CO2 output of simply burning fuel, since CO2 is an input to the system from sequestration of coal and LPG plants) and anyone (not just an international oil superpower) can invest in plants. Produce fuel locally where overproduction of green power happens (like, near any wind farm) and the energy input becomes free and green. Many companies are working on this tech, including the US Navy. Again, this is not vaporware, this is a reality that has been done since WWII...

I'm sure the technology is there to convert algae sugars into fuel, but I seriously doubt it will amount to anything on the industrial scale we need to replace part of our current fuel consumption.

For one thing, growing algae requires tremendous amounts of water and the tanks also need a substantial surface area. While pumping water from the ocean could solve the former, there's not many suitable coastal locations that are not arable lands in the U.S.

Actually, as I mentioned in the article, "Seaweeds do not require arable land, fertilizer, or fresh water..."

No, it doesan;t require arable land. It does require massive tracts of ocean though. Even at 100% efficincy, (every possible drop of ethanol squeesed from seaweed), it would take an ocean based facility the size of a few states in geographic area to even replace half of our ethanol. seaweed grows slower, has less sugar total available to turn into ethanol, and grows flat to the surface as opposed to a 3D multi-foot high mass of material grasses become. The rotations of crop per year, resulting in mass of ethanol per sqmi is dramatically less with seaweed, making the ocean spoace needed for a farm many times grteater than the existing landbased crop area.

The logistics alone of a seabased operation on that scale are insane, and have you even considdered the environmental (most WEEATHER related) impacts of turning a couple hundred sq miles of open ocean into a new color, creationg either a heat trap or reflection area that would radically change the water temperature? (not to mention the impact to the wildlife having their swimming area taken from them)

Also, switchgrass is basically a weed. It grown in land we honestly can;t USE for much food. It's also used as a rotational crop when a field has been over-depleted of other nutirents, so using grass for ethanol really has little impact on food price (going forward, we've been doing it for 9 years now, the impact should have long been felt, and it was). We're also reportedly considdering going back to MBTE, since it was found MBTE was in fact NOT the environmental issue in fuel leaks as the EPA thought, it;s the other fuel additives, and MBTE could safely again replace ethanol, and would also result in a return to a better fuel economy.

seaweed grows slower, has less sugar total available to turn into ethanol, and grows flat to the surface as opposed to a 3D multi-foot high mass of material grasses become.

Hmm, so based on this line of thought, we need to find some way to turn bamboo into a fuel. It grows quickly, can get very tall before being harvested and while it takes landspace, it grows so quickly and replenishes itself well

seaweed grows slower, has less sugar total available to turn into ethanol, and grows flat to the surface as opposed to a 3D multi-foot high mass of material grasses become.

Hmm, so based on this line of thought, we need to find some way to turn bamboo into a fuel. It grows quickly, can get very tall before being harvested and while it takes landspace, it grows so quickly and replenishes itself well

There are species of seaweed that can grow 2ft a day....... why is it slow again?

As for the Oh NOES! what if the e.coli get out?! Typically bacteria made in labs are not hardy and are not suitable for commercial use without much more work. Besides, they e.coli can be made as fragile as needed as well.

I wonder if producing methane would not be more useful - we already have an extensive infrastructure, and the resulting fuel could be used not just in current vehicles (with minor modification) but also in any heating, cooking, and power generation applications.

No, methane is hard to handle: Not only you have to transport it through either pipelines (expensive) or bulky pressurized cans, it's a potent greenhouse gas when leaked. The energy density is also not as high as ethanol

Well, it's hard-er than liquid fuels, yes. (Though separating it from the production tank would probably be much easier.) But importantly, it's an already-solved problem in that we have a very large infrastructure that already exists dedicated for this task. Even more importantly, it's a far more versatile fuel that's already in use on a large scale in industrial, commerical, and residential settings. Most importantly of all, we have ample fossil reserves that can relatively easily be used to backstop any volatitility in the renewable supply, making it economically promising.

All of the same could be said of ethanol (aside from the versatility, not so sure about that one). In fact, nearly all gasoline at the pump *already* has ethanol in it, so there you go.

switchgrass is basically a weed. It grown in land we honestly can;t USE for much food. It's also used as a rotational crop when a field has been over-depleted of other nutirents, so using grass for ethanol really has little impact on food price (going forward, we've been doing it for 9 years now, the impact should have long been felt, and it was).

That's a bit of a jumble so I'm not sure exactly what you are trying to say. Certainly switchgrass can be used for feed. And as lower lignin varieties are bred, it will be more so. If building soil is the goal, leave all the plant. So yes, going forward, switchgrass does have a negative impact on food. Unlike corn ethanol which has had little impact beyond the vast amount of ignorant hysteria.

I did some quick calculations and get one liter of ethanol for 3.5kg of kombu. Replacing the world's current ethanol production of 51 billion liters with this would require about 173 million tons of kombu. Current worldwide harvests are already somewhere between a couple and a few million tons, but I can't find solid data on whether that is wet or dry mass.

For those fearing ecological consequences, kelp actually helps boost the environment by, for example, providing places for young fish to hide while growing. This allows more to survive to sexual maturity, meaning more fish reproducing. The economic benefits of massive kelp farming could be substantial to the host nation not only in lower oil imports but also improved fishing. Depending on what's left over, it could also provide a good source of nitrogen in fertilizers, making the country less reliant on urea. And it can be exported to landlocked nations.

The harvesting could be relatively simple, too. Two boats on either side of a bed move forward with an underwater cutter that floats at a specific depth, cutting the help and letting it float to the surface. Another vessel comes along and basically scoops it up.

If they can do butanol at these rates and enough shallow water can be found without creating a navigation hazard, it might create a viable alternative source.

Cool. So when these get released into the wild they'll dissolve every last piece of algae in our oceans and elevate the alcohol content to levels toxic to all denizens thereof. But the good news is we'll be able to drink seawater and get shitfaced.

I laughed a bit at this as I thought that sounded like a great idea and would make for a fun trip to the beach. Then I remembered about E. Coli infections:

Severe stomach cramps and stomach tenderness. Diarrhea, watery at first, but often becoming very bloody. Nausea and vomiting. (credit: WebMD)